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This paper treats the problem of setting the inventory level and optimizing the buffer allocation of closed-loop flow lines operating under the constant-work-in-process (CONWIP) protocol. We solve a very large but simple linear program that models an entire simulation run of a closed-loop flow line in discrete time to determine a production rate estimate of the system. This approach introduced in Helber, Schimmelpfeng, Stolletz, and Lagershausen (2011) for open flow lines with limited buffer capacities is extended to closed-loop CONWIP flow lines. Via this method, both the CONWIP level and the buffer allocation can be optimized simultaneously. The first part of a numerical study deals with the accuracy of the method. In the second part, we focus on the relationship between the CONWIP inventory level and the short-term profit. The accuracy of the method turns out to be best for such configurations that maximize production rate and/or short-term profit.

One of the key problems in every company, including small and medium enterprises, is how to determine the inventory level for each product that will be sold to their customers appropriately as it can suppress the build up of inventory as well as avoid the stock out. This study is aimed to understand the behavior of consumers in purchasing the products so it can be used to predict the purchasing for the next period. Later, the prediction is used as a decision support in determining the appropriate amount of inventory for each product. The study was conducted at Karomah Brass, a small and medium enterprise engaged in the sale of antique furniture accessories in which the company doesn’t produce its own products but buys from the supplier. The methods that used in this study are the Market Basket Analysis (MBA) and Artificial Neural Network (ANN) Back propagation. MBA is used to examine the buying behavior of customer while ANN Back propagation is used to predict product inventory's requirements/needs for each product. The results discover that the customers frequently purchase products that serve as a kind of antique closet accessories and if customer bought that certain product, then they will also buy similar products in accordance with 21 rules that have been obtained from the mining of transaction data. Whereas, other result shows the prediction of the amount product inventory requirements/needs for one year to the next.

This paper presents a real case study conducted in Egypt in which discrete-event simulation model was developed to simulate the supply chain's behavior of the contraception methods for Egypt Ministry of Health (MOH). SIMIO simulation modelling tool was used for the implementation to effectively model and analyze the real system behavior, in addition to providing an effective means for supporting the decision making process through insightful analysis and representations of the number of served customer over time and the inventory level across various warehouses.

The purpose of this paper is to design a new periodic ordering system which is able to control both the order quantity fluctuation and the inventory level flucutation. The feature of this scheme is to obtain the order quantity by the typical periodic ordering system and to reduce the order quantity by using a regulation coefficient “G” ( \( 0.0 \leqq G \leqq 1.0 \) ) when the order quantity exceeds the limits. Hereafter we call the new periodic ordering system G control rule system. As a result of several simulations, we could obtain better results than that of the typical periodic ordering system in criterion value. Therefore, we make further development the G control rule system in the production-inventory control system, the similar result was obtained in controlling both the production quantity fluctuation and the inventory level fluctuation.

The primary objective of a regional blood distribution system is to maintain adequate inventories of blood at each of the hospital blood banks in the region with a maximum of blood utilization within its limited lifetime. The institution of a predictive regional planning system operating under the objective of overall regional efficiency has significantly improved both utilization and availability. The system is applicable to any region and provides a mechanism for effective collaboration between regions.

Manufacturing efficiency has too distinct aspects: the procedural aspect that deals with the input-output relations of the manufacturing process and the logistical aspect that deals with the question of what item to manufacture in what quantity and at what time. The latter aspect is part of the overall logistical control that governs the operational planning of every company.

The collection, storage and allocation of human blood for transfusion patients presents a problem unlike those encountered in the production, storage and distribution of industrial products. Blood cannot be produced at will, but has to be donated by healthy humans on a voluntary basis. In addition blood cannot be transfused into any patient, but the compatibility between the patient’s and the donor’s blood has to be tested beforehand (“crossmatching”). There are eight different main blood groups (A, B, O, AB with Rh+ or Rh-), which are basically not compatible with each other. This would not be a problem if the distribution of the main blood groups within the population was not highly unequal with some very rare groups. The inventory problem is further complicated by the fact that human blood has a limited life span of 3 to 4 weeks.

Capacity planning, production scheduling and control are among the most time consuming and laborious tasks in production management. There are a host of independent factors which include the degree of job and resource flexibility, machine loading and priority despatch rules, stock and inventory level, operations costs and other cost related factors. All these considerations affect various production organisation policies as well as manufacturing systems layout considerations. This paper presents an algorithm which determines the idle time of machines and waiting time of jobs, without having to calculate the starting and finishing times of all the operations on all the jobs.

An approximate reasoning framework is proposed based on the developments in interval valued fuzzy set representation and inference. A detailed study of the aggregate production planning problem and its comparison with a classical operations management model known as HMMS model show that the approximate reasoning framework produces a favourably robust result.

We are concerned here with a particular instance of an inventory model usually referred to in the literature as the Economic Lot-Size Model. Our objective is, roughly, to determine which is the best inventory policy one could adopt under certain conditions, with one objective being, of course, to ensure that costs incurred are kept at a minimum.

Publisher Summary This chapter describes the price coordination mechanism for hierarchical decision making and discusses the way in which the results of coordination may be useful in determining where structural changes—if possible—should be made in the dynamic system to achieve better performance. By properly adapting the price mechanism, a two-level structure for complex systems can be developed with inventories. In this structure, hierarchical optimization is used periodically at the higher level, and lower-level controllers track the model optimal inventory level with reasonable accuracy based on on-line measurements. The chapter presents a brief description of the interaction balance method (IBM)—the basic hierarchical optimization algorithm in which price coordination is used.

In this chapter, a social system model will be postulated to serve as a starting point for a further analysis. The systems approach is first to construct a model of great generality with which one can, by setting certain restrictive conditions, generate certain classes of more specific systems. In other words, the general model of the social system or paradigm serves as a basis for a classification to be elaborated on further in this chapter.

In this paper we consider a single product production/inventory model with the following characteristics. The production facility can be either on with producing rate 1, or off. The produced goods are stored in a buffer with capacity M. The inventory level is controlled by a (m,M)-switch-over policy with 0

As will be stressed throughout this book, the average manufacturing operation is extremely complex to manage. The work of several hundred people and dozens of machines has to be coordinated to produce hundreds of product types, and it is not surprising that managers have frequently failed to control such a complex operation effectively.

During the past decade, materials managers have made considerable progress in the coordination and integration of their activities, but many pitfalls and problems remain in the implementation of materials management programs. Uncoordinated cost reduction, for example, can be misleading; cost reductions in one area frequently appear as cost increases elsewhere. Reducing in-plant transportation equipment in order to fully utilize all of the company’s forklifts would probably require inventory increases and delay production. Similarly, reductions in packaging costs can increase the costs of materials handling and customer claims.

Frankly speaking, when I was asked to make a paper on a tremendous theme, “Corporate Systematic Thinking and Its Implementation”, I was not self-confident in my own abilities.

This paper reports on the results of research intended to examine the impact of capacity level on the performances of different lot sizing rules in a multiproduct, multistage system using Material Requirements Planning. The results are measured on the basis of frequency of stockouts, number of setups and average dollar inventory level, and total inventory cost. Although the impact of capacity level on the relative performance of different lot sizing rules is not as significant as originally suspected, it is an important factor along with other factors to be considered in choosing an appropriate decision rule. Our findings also brought out several points which do not confirm many previous studies.

A continuous revies (s, S) inventory system with renewal demand in which one item is put into operation as an exhibiting piece is analyzed. The lifetime of any operating unit has Erlangian distribution, and on failure is replaced by another one from the stock and the failed item is disposed of. Replenishment of stock is instantaneous. The transient and stationary values of inventory level distribution and the mean reorder rate are obtained using the techniques of semi-regenerative processes. Decision rules for optimum s and S that minimize the long-run expected cost rate are derived. The solution for a dual model with the distribution of lifetimes and inter-demand times interchanged is also given. ? 1989 The Institute of Statistical Mathematics.

Everyone agrees that a "picture is worth a thousand words". However, it is not yet obvious that it would make good business sense for managers to make liberal use of Computer Graphing in almost all phases of business decision-making. This paper asserts that it is convenient and practical where something worthwhile can be gained by study of variation of such important parameters as demand, inventory level, or sales, with time or with respect to another independent variable.

Due to sluggish transformation rates of metastable phases, unalloyed Pu continues to shrink after casting. Therefore, a pre-machining holding period is required to promote finished part dimensional stability. This test will determine the holding period commensurate with both this requirement for stability and an optimum material inventory level. Four storage periods will be evaluated (9, 8, 7, 6 days) for dimensional changes and related to parts stored for the standard 10-day period.

Blood transfusion is potentially one of the most hazardous therapeutic measures in the modern hospital. Some of these hazards can be reduced by improvement in clerical efficiency and others by a better understanding of the risks of transfusion at the medical level. To achieve these aims automation, using computer programming methods, has been introduced into a large hospital. Clerical efficiency has been increased by a specially designed blood transfusion request form which carries all the necessary clinical and technical data. This information is transcribed to punch cards and then compared, using standard computer techniques with other listings such as patients’ admission data to ensure proper identifications and with past history of previous serological examinations and blood transfusions and reactions. The original request form is used during laboratory processing and this blood grouping data and crossmatch data is also punched for the permanent file. The admission file provides information of the diagnosis and planned surgical procedures. This permits prediction of immediate blood needs by the transfusion service resulting in more efficient management of blood bank inventory and a consequent reduction in storage time and avoiding the keeping of stocks which are near the end of their useful life. It is proposed to define the elements of logical decision making involved in the use of blood transfusion taking into account such factors as patients’ age, sex, nutritional status, operative procedure, associated diseases, etc. By providing a firm scientific background of the indications for blood transfusion there will be established a therapeutic index, i.e., the ratio of therapeutic value to potential risk. This will enable more rational control of blood transfusion requirements both at the inventory level and at the medical level.

Measuring the contribution of interorganizational systems (IOS) is challenging, and mainly based on subjective surveys. The purpose of this study is to objectively examine the effectiveness of IOS, through data from corporate financial statements. We developed a novel performance measure: an effectiveness ratio that reflects changes in average inventory level in comparison with change in annual sales. This measure reflects a certain aspect of improvement in supply chain management achieved by the evident developments of IOS, while considering external events that affected the companies. Two samples of American and Israeli companies were used for developing and empirically examining the suggested effectiveness ratio over 20 years (1993-2012). The results show considerable improvement as measured by the average effectiveness ratio of randomly selected American international companies in the cosmetics and toiletry products sector. However, the Israeli sample of food suppliers and importers, showed average ma...

This paper deals with the question of optimal inventory sizes in a competitive environment in which the demand for a product at a vendor depends on the inventory level of the product at that vendor relative to the inventories of the same product held by other competing vendors. The total demand for the product at all vendors is assumed to be fixed. This question is examined for two different replenishment policies: base stock policy where the vendors keep a constant level of inventory by ordering the product at the same rate as the observed demand; and continuons review policy where all vendors replenish their inventories periodically when the inventory level drops to a predetermined level.

This note provides the methodology to construct a set of indifference curves that permit the exact determination of the optimal inventory level in a system where items are restocked one at a time and unsatisfied demand is lost. An illustrative set of curves is shown.

In this paper we report the results of analyses which indicate that traditional thought on the relationship between stockout frequency, inventory level, capacity level, and inventory rules should be re-examined. A significant finding is that lot-sizing rules can affect aggregate plans as they relate to capacity requirements.

The allowed safety stock level reduction and accompanying reduction in average on-shelf inventory level are evaluated, for prescribed system performance requirements, as a function of mean leadtime reduction. The general simulation technique developed for this purpose allows the treatment of the s, S periodic review inventory problem with both demands and leadtime being stochastic. Some results obtained for a military supply system, where the reduction in leadtime is achieved by resorting to airlift rather than sealift, are presented. In addition, generalizations as to the effect of certain parameters on the reductions allowable for general situations are given. Finally, a simplified means of predicting these effects by an empirical method is indicated.

This paper is concerned with answering the question: what should be the optimum inventory level for two items A, B at the beginning of a period on which uncertain requirements for inventory will occur.